The present invention relates to an occupant protection system and, more particularly, to an apparatus and method for detecting a vehicle rollover event for use with an actuatable occupant rollover protection device.
To detect a vehicle rollover event, a vehicle may be equipped with one or more sensors that detect vehicle dynamics. The sensors are connected to a controller that evaluates the sensor signals and controls actuation of one or more actuatable devices in response to a determined occurrence of a vehicle rollover event.
U.S. Pat. No. 5,825,284 discloses a vehicle rollover system having an acceleration sensor that provides a signal indicative of lateral acceleration of the vehicle. A processor calculates a roll-moment based on the sensor signal and provides a visual display indicating the likelihood of vehicle rollover.
U.S. Pat. No. 5,610,575 and U.S. Pat. No. 5,890,084 disclose other approaches to rollover detection.
In accordance with the present invention, a rollover sensor monitors vehicle roll and an accelerometer monitors lateral vehicle acceleration. The signal from the rollover sensor is compared against one of two thresholds in response to the sensed lateral acceleration. An occupant protection device is actuated in response to the rollover sensor comparison.
In accordance with one aspect of the present invention, an apparatus detects a vehicle rollover event. The apparatus includes a rollover sensor for sensing vehicle roll and providing a signal indicative of vehicle roll about a front-to-rear axis of the vehicle. An accelerometer senses vehicle acceleration in a direction offset from the front-to-rear axis of the vehicle and provides an acceleration signal indicative thereof. The apparatus further includes a controller for comparing the signal from the rollover sensor against a first rollover threshold when the acceleration signal is less than an acceleration threshold and for comparing the signal from the rollover sensor against a second rollover threshold when the acceleration signal is equal to or greater than the acceleration threshold. The controller indicates a vehicle rollover condition when the signal from the rollover sensor is greater than the threshold it is compared against.
In accordance with another aspect of the present invention, a method detects a vehicle rollover event comprising the steps of sensing vehicle roll and providing a roll signal indicative of vehicle roll about a front-to-rear axis of the vehicle, sensing vehicle acceleration in a direction offset from the front-to-rear axis of the vehicle and providing an acceleration signal indicative thereof, comparing the roll signal against a first rollover threshold when the acceleration signal is less than an acceleration threshold and for comparing the roll signal against a second rollover threshold when the acceleration signal is equal to or greater than the acceleration threshold and for indicating a vehicle rollover condition when the roll signal is greater than the threshold it is compared against.